i just had both of my lower units rebuilt and one of them started to give me problems yesterday. I have twin VP duo prop dpsm units that was running great for about five hours total since rebuild. Yesterday we shutdown to swim and when we started back up I put it in reverse and would hear a whirring sound from the starboard drive. I put it in forward and everything sounded fine. I shut her down and got in the water to turn the props by hand and when in neutral I can feel the every gear tooth when I turn the prop in either direction. It's not extremely hard to turn or anything but you can definitely tell there's something going on. Anyone have any ideas as to what it might be?